Objective: To compare the treatment outcomes of intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) alone to concurrent chemoradiotherapy (CCRT) for locoregionally advanced nasopharyngeal carcinoma (NPC). Methods: From November 2001 to December 2009, 333 patients with pathologically diagnosed, locoregionally advanced NPC were treated by IMRT-SIB with or without weekly cisplatin concurrent chemotherapy at our institute. Among them, 62 patients received neo- or adjuvant chemotherapy or molecular target drugs were excluded from this analysis. There were 129 patients received IMRT-SIB alone, and 142 patients received IMRT-SIB with weekly cisplatin 30 mg/m2 for 7 weeks. The radiotherapy protocol was identical for each group. Results: There were no significant differences in survival between CCRT and IMRT-SIB group in terms of gender, T/N classifications and concurrent chemoradiotherapy. The 5-year local control (LC), overall survival (OS), disease-free survival (DFS) and distant metastasis-free survival (DMFS) for the entire group were 87.0%, 79.4%, 69.7 and 83.3%, respectively. The LC, OS, DFS and DMFS for CCRT and IMRT-SIB alone groups were 80.6% vs. 90.8% (P = 0.10), 71.7% vs. 83.2% (P = 0.201), 63.9% vs. 74.6% (P = 0.07), and 79.6% vs. 86.0% (P = 0.27), respectively. Conclusion: Compared to CCRT, IMRT-SIB alone had demonstrated similar disease LC, OS, DFS and DMFS in locoregionally advanced NPC. Careful radiation target volume design and simultaneous integrated boost may play a role that overrides the benefit from concurrent chemotherapy. Further investigation with randomized study is necessary to determine whether IMRT-SIB alone can achieve similar outcomes of concurrent chemoradiotherapy.